Effect of propofol on noise-induced hearing loss in guinea pigs

Abstract

Objective To evaluate the effect of propofol on noise-induced hearing loss in guinea pigs.Methods Forty-eight healthy adult male guinea pigs,aged 3 months,weighing 400-500 g,were randomly divided into 4 groups (n =12 each) using a random number table:control grotup (C group),propofol group (P group),noise-induced hearing loss group (N group),and propofol + noise-induced hearing loss group (P + N group).A loading dose of propofol 5 mg/kg was infused intravenously over 5 min,followed by infusion at 20 mg· kg-1 · h-1 for 115 min in P and P + N groups,while the equal volume of normal saline was given in N group.N and P+ N groups were exposed to the noise of 4 kHz center frequency and 118-122 dB sound pressure level for 120 min.Distortion product otoacoustic emission (DPOAE) was measured before noise exposure (T1) and at 1 h after the end of noise exposure (T2) and the amplitudes were recorded at the frequencies of 2,4,6 and 8 kHz.After the second measurement of DPOAE,all the animals were sacrificed and organs of Corti were harvested for determination of cochlear 8-isoprostaglandin F(2alpha) (8-iso-PGF2α) content (by ELISA assay) and out hair cell (OHC) count.The rate of OHC lesions was calculated.Results The DPOAE amplitude was significantly lower at frequencies of 4,6 and 8 kHz at T2 than at T1 in N and P + N groups (P ＜ 0.05).Compared with C group,the DPOAE amplitude was significantly decreased at frequencies of 4,6 and 8 kHz at T2,while the cochlear 8-isoPGF2α content and rate of OHC lesions were increased in N and P + N groups (P ＜ 0.05).Compared with N group,the DPOAE amplitude was significantly increased at frequencies of 4,6 and 8 kHz at T2,while the cochlear 8-iso-PGF2α content and rate of OHC lesion were decreased in P + N group (P ＜ 0.05).Conclusion Propofol can reduce noise-induced hearing loss in guinea pigs possibility through decreasing oxidative stress response-induced damage to cochlear OHCs. Key words: Propofol ; Hearing loss, noise-induced